Main cutting insert of a masonry drill bit



FIG. 1 is a front view of a main cutting insert of a masonry drill bit bearing the design;

FIG. 2 is a back side view of the main cutting insert of FIG. 1;

FIG. 3 is a left side view of the main cutting insert of FIG. 1;

FIG. 4 is a right view of the main cutting insert of FIG. 1;

FIG. 5 is a top view of the main cutting insert of FIG. 1;

FIG. 6 is a bottom view of the main cutting insert of FIG. 1;

FIG. 7 is a perspective view of the main cutting insert of FIG. 1; and,

FIG. 8 is a perspective view showing the main cutting insert of FIG. 1 in a masonry drill bit.

The portions in broken lines form no part of the claimed design. 

CLAIM The ornamental design for a main cutting insert of a masonry drill bit, as shown and described. 